In a population of 930,000 inhabitants all records of native valve infective endocarditis diagnosed in the decade 1980-89 were reviewed. Using strict case definitions 132 clinically well-defined or post-mortem diagnosed cases were found. Included were cases referred to the local department of cardiology, as well as cases treated in non-specialized departments. Of 132 cases found 23 were only diagnosed post mortem. The male/female ratio was 71/61. The median prehospital duration of symptoms was 20 days (range 0-180 days) and the median in-hospital diagnostic delay was 5 days (range 0-54 days). Known cardiac disease was found in 42% of cases, a possible portal of entry was found in 33%, but in 36% there were no predisposing factors. Remarkably, only two patients had known rheumatic heart disease and none had a known dental focus. During the clinical course 55% experienced cardiac failure and 17% embolic episodes. In 19 patients surgery was required. Of 111 culture-positive cases streptococci were found in 61 and staphylococci in 45 cases. Echocardiography was performed in 95 cases with echocardiographic signs of endocarditis in 65 patients. Overall mortality was 33% with a mortality in clinically diagnosed cases of 18%. Of 14 cases needing immediate surgical intervention, two died.